OFFSET
1,1
COMMENTS
Numbers where floor(n/10^floor(log(n)))^2 divides n.
LINKS
Christian N. K. Anderson, Table of n, a(n) for n = 1..10000
Christian N. K. Anderson, Ulam Spiral for the first 10000 terms. [Draw the usual Ulam spiral, containing all the nonnegative integers, and color the numbers belonging to this sequence yellow]
EXAMPLE
48 is divisible by 4^2.
PROG
(R)
x=0; y=rep(0, 1000); len=0
firstdig<-function(x) as.numeric(substr(as.character(x), 1, 1))
isint<-function(x) x==as.integer(x)
while(len<10000) if((fd=firstdig((x=x+1)))>1) if(isint(x/fd^2)) y[(len=len+1)]=x
CROSSREFS
KEYWORD
nonn,base
AUTHOR
Kevin L. Schwartz and Christian N. K. Anderson, May 04 2013
STATUS
approved